DE2853611A1 - ARRANGEMENT FOR SUPPRESSING IMPURITIES CAUSED BY COLOR COMPONENTS IN THE LUMINANCE SIGNAL IN A TELEVISION SIGNAL PROCESSING DEVICE - Google Patents

Description

ECA 72.057

π.S. Serial Wo: 859.922

Filed: December 12, 1977

RCA Corporation, New York, Ii.Y., V.St.v.A.

Arrangement; for suppressing impurities in the luminance signal caused by chrominance components in a television signal processing device

The invention relates to systems in which color television signal are processed, and specifically relates to an arrangement for suppressing to be provided in such a system of disruptive influences of the chrominance signal in the luminance signal caused by abrupt phase changes in the chrominance signal can be caused.

A reproduced on the basis of a picture-characteristic video signal Color image is mainly defined by the luminance and chrominance components of the video signal. A color television signal processing System such as a color television receiver usually includes a chrominance channel for processing the chrominance component excluding the luminance component and a luminance channel for processing the luminance component excluding the chromaticity component.

With a conventional NTSC color television receiver, the Quality of the reproduced image depends significantly on after which method and to what extent the chrominance and luminance information contained in the demodulated video signal mixture separated from each other. A common technique in processing the luminance component of the NTSC television signal consists in placing one on the. Luminance channel at the entrance

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Color subcarrier frequency tuned bandstop filter to provide filter out most of the chrominance signal frequencies and thereby prevent those processed by the luminance channel Signals are disturbed by the chrominance signals. The circuit arrangement used to process the chrominance signals there is usually a bandpass behavior, so that there is luminance signal frequencies below a given frequency (e.g. below 3.1 MHz) suppressed xverden.

However, this method of separation does not optimally solve the problem of preventing or compensating for mutual interference between the luminance and chrominance components. In particular, the chrominance band-stop filter (color trap) in the luminance channel is not able to completely suppress all chrominance information, since its construction is based on a compromise. This notch filter has very little or no blocking effect for signal frequencies below about 5.1 MHz. The frequencies of the chrominance signal that are not suppressed by the notch filter (ie sidebands) have a disruptive influence on the luminance, which causes disruptive spots at the edges in areas of fine details of the image. If the notch filter does not attenuate the entire frequency band of the chrominance signals, this results in a creeping pattern of spots (dot crawl) at vertical edges. This undesirable effect is intensified if measures for horizontal control are taken in the luminance channel.

More precisely, the quality of a reproduced color image can be affected by the occurrence of abrupt transitions in the color phase (i.e. in the case of hue jumps), which indicates the presence of incorrect (dissimilar) color phase information corresponds to within the horizontal scanning interval. Such transitions or jumps produce sideband components of the color subcarrier, which can "contaminate" the luminance signal and lead to so-called "edge spots" in a reproduced Lead image. The edge spots appear at points of a color transition in the image and are particularly noticeable when

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a color transition is repeated over several horizontal picture lines within the same frame. In this jail expresses itself
the disturbance in the form of edge spots that seem to move slowly upwards in the image along the (vertical) transition area of the colors.

When a rapid transition, from a color phase (hue) to
If another phase leads to sideband components in the color subcarrier which fall beyond the blocking range of the chrominance blocking filter usually contained in the luminance channel, then these sideband components can pass through the luminance channel and change the luminance signal so that blemishes are visible on the reproduced image. the
disturbing sideband components produce the edge corners visible in the reproduced picture by increasing the amplitude
of the luminance signal, the contrast of the reproduced
Image determined to change during the time of the color phase transition.

The extent of the stain disturbance depends on how strong and how fast the jumps in the color phase are. The blotch disturbance is more pronounced (ie, more visible) when there is a rapid transition between phases within a given horizontal line
for very dissimilar colors (e.g. from the color phase for yellow to the color phase for cyan). The disturbance is less pronounced if the transition occurs more slowly within a given horizontal line and / or between phases of closely related colors (e.g. from the color phase for yellow to the color phase for flesh tone). On the other hand, however, there can also be a stain disorder that is less pronounced under the circumstances mentioned above
would become strong when there is a significant change in color saturation at the same time. It is therefore desirable, in order to improve the quality of a reproduced color image, to reduce the adverse effects due to uncorrelated chrominance information.

One to this. Purpose devised system is in US patent application He. 778, -594-, which has a continuation-in-part

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Application for US patent application Er. 678,594- is which one on your part corresponds to the German patent application P 27 17 253.8-31. In this system, the gain factor of a comb filter, that to separate the frequency-intermingled luminance and chrominance components of a composite color television signal is used, depending on the presence of incorrect chrominance information controlled to the otherwise visible effects caused by contamination of the luminance signal with the incorrect Chroma information can be caused to suppress.

The invention is based on a system of the type described in the preamble of claim 1, i.e. a system that the luminance and the type of color of a reproduced color image depending on the image-characteristic luminance and Controls chrominance components of a color television signal. The chrominance component consists of modulated color subcarrier oscillations with a parameter that may change abruptly, some of these hops being associated with sideband components of the subcarrier that create undesirable interference of the reproduced image, if they have a significant influence on the luminance of the reproduced image Image can be exercised. The system also contains a frequency-selective one Circuit which lets the color television signal pass frequencies that are based on a color component Frequency band are limited. The object of the invention is to provide an arrangement which in such System improves the quality of the reproduced color image.

This object is achieved according to the invention with the in claim 1 marked features solved. Accordingly, the arrangement according to the invention contains a signal delaying network that the from the frequency-selective circuit transmitted signals delayed by a predetermined amount, which is an interval corresponds, during which one of the specifically mentioned sudden transitions can take place. The arrangement according to the invention further includes circuitry (e.g., a signal multiplier) which selectively passes the delayed signals from the output of the delay network and, on the other hand, without delay

Gerte selectively let through signals from the output of the frequency-selective Circuit receives and develops an output signal from it, which indicates the presence of one of the specially mentioned abrupt transitions. This output signal is then exploited in order to prevent that the Parbhilfsträgerkomponenten associated with the transition, the luminance of the reproduced Significantly affect the color image.

Advantageous embodiments and developments of the invention are characterized in the subclaims. Details of the invention are explained in more detail below using exemplary embodiments with reference to drawings.

Figure 1 shows in block form part of a color television receiver, which contains an arrangement according to the invention;

Figures 2 to 5 are circuit diagrams for part of the arrangement according to Figure 1;

Figures 6 and 7 show frequency response curves as they are in operation the arrangement according to Figures 1 and 2 to 5 are effective.

The following is an example of a television signal processing System described for the MDSC television standard used in the USA is designed. Referring to Figure 1, a color television signal source 10 provides received RF signals using conventional RF signals responsive processing circuits a composite color television signal (color television signal mixture), the chrominance and contains luminance components.

The chrominance component of the output signal of the source 10 is a frequency-selective circuit 12, which the frequency band the chrominance information selectively passes to the input a limiter 15 and the input of a delay unit 32 coupled, which causes a signal delay by a predetermined amount, in the example described here by approximately 140 Nanoseconds. The output from the delay unit 32 The delayed chrominance signal is amplified in a limiter 40 and limited and then an input of a signal multi-

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plier 25 fed to the type of a synchronous detector. A other input of multiplier 25 receives from the output of the limiter 15 amplified and limited instantaneous chrominance signals.

The limiters 15 and 40 are used to amplitude changes the delayed and undelayed chrominance signals given to the multiplier 25. The multiplier 25 operates hereby as phase detector. It provides an output signal which is characteristic of the phase correlation of the chrominance signal during each binding line by showing the relative phases who feels delayed and undelayed chrominance signals. The output of the multiplier 25 is then experienced low-pass filtering and inversion in circuits 60 and 68, respectively.

An envelope detector 44 senses the amplitude envelope of the delayed signal in order with its output signal the presence of relatively long-duration signals (i.e. chrominance signals) within the chrominance transmission range. The output signal of the envelope curve detector 44 is based on the an input of a coincidence amplifier 74 coupled, the other input receives the output signal from inverter 68. One from amplifier 74- based on these two inputs The generated control signal indicates that at the same time a relatively high color saturation and a change in hue (i.e. incorrect Color phase information) is present when chrominance signals available. This control signal is used to control the operation of a switching device 82, the assemblies for signal transmission and for switching.

The video signals coming from the source 10 are also coupled via a delay network 90 and via the switching device 82 to a luminance signal processing unit 100, specifically via a chrominance filter 95 1 which is tuned to 3.58 MHz and which is usually contained in a luminance channel 80 is to attenuate the frequencies belonging to the chrominance signal. The delay network 30 is used for

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Delay compensation by using the signals coming from the source delayed by an amount equal to the signal delay from the input of the frequency-selective circuit 12 to the output of the Amplifier 74-. The switching device 82 is at 3.58 MHz tuned chrominance frequency every 87 connected to this frequency trap 87 can optionally be coupled with the luminance channel or to decouple from the luminance channel, depending on whether the control signal from the output of amplifier 74- a presence or indicates the lack of incorrect color phase information. This Operation will be explained in more detail below.

The chrominance signals from the output of the frequency selective circuit

12 are also referred to a chrominance signal processing unit

13 coupled to the color difference signals therefrom in a known manner Derive E-Y, B-Y and G-Y. The color difference signals are combined in a combining circuit 105 with a luminance signal T from the output of the luminance processing unit 100 combined to derive the color signals E, B and G, which are then coupled to the inputs of a color picture tube 110.

The circuit diagrams in Figures 2 to 5 show details of the part of Figure 1 framed with dashed lines. According to Figure 2, video signals from the source 10 via an as Serving buffer and arranged in the form of an emitter follower transistor 211 and one of ohmic, inductive and capacitive Components formed chrominance band filter 12 coupled to the base input of a transistor 215, which is an amplifier and puff he forms. At the collector of transistor 215 amplified, filtered chrominance signals appear, which the limiter 15 are supplied, which according to Figure 2 is an amplifier transistor 220 and an emitter-coupled transistor pair 222, 224, which are arranged in the form of a differential amplifier are. Amplitude-limited chrominance signals appear at the collector output of transistor 224 and thus at terminal 1.

The emitter of transistor 215 will be of low impedance Chrominance signals coupled to the delay unit 32, the in the example shown in Figure 2, a chain of Lc deceleration

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is gerungsgÜedern. From the output of the unit 32 get delayed chrominance signals via the coil output of a inserted amplifier transistor 230 to the limiter 40. The limiter 40 includes an amplifier transistor 231 and two emitter-coupled transistors 232 and 234, which act as differential amplifiers are switched. At the collector output of the transistor 234 and thus at terminal 2, amplitude-limited delayed chrominance signals appear. Delayed chrominance signals also appear at a terminal 3, namely via an as Emitter Follower Switched Transistor 237

FIG. 3 shows embodiments for the signal multiplier 25, the low-pass filter 60 and the inverter 68. The Multiplier 25 receives amplitude-limited input signals - undelayed chrominance signals from terminal 1 and amplitude-limited delayed chrominance signals from the terminal 2. The multiplier 25 contains a first, subordinate transistor pair 320, 322 in differential connection and a second and third upper-level transistor pair 324, 325 and 326, 327, each also in differential circuit. The undelayed ones Chroma signals from terminal 1 are coupled to a base input of transistor 320, and delayed chrominance signals from terminal 2 to the basic inputs of the Transistors 324 and 326 coupled. The output circuit of the multiplier 25 contains the low-pass filter 60, which consists of Collector load resistors 342 and 345 and a capacitor 341 exists and between the common collector connection of the transistors 324, 325 and the common collector connection of transistors 326 and 327 is switched.

The ones at the coupled collectors of the transistors 324, 325 and 326, 327 appearing output signals coupled to the inputs of the inverter 68, which in the illustrated case has two transistors arranged in a differential circuit 351 and 355. At the collector output of the transistor 351 an "inverted" signal appears (i.e. inverted with respect to that at the common collector terminal of the Transistors 324, 325 of the multiplier 25 appear

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Signal), and this signal is applied to the AND gate via a transistor 370 connected as an emitter follower and a terminal 4 74 given.

Circuitry for the amplifier 74 and the envelope detector 44 is shown in FIG. The delayed chrominance signals appearing at terminal 3 (FIG. 2) are connected to an envelope detector network via an amplifier transistor 416 and a transistor 429 connected as an emitter follower coupled, which is a detector diode 435 and contains a low pass filter network formed by a resistor 444 and capacitors 442, 445. About transistors 452 and 456 is then an envelope signal on the Base electrode of a transistor 461, which forms an input terminal of the amplifier 74.

In addition to the input transistor, the amplifier 74 comprises 461 an emitter-coupled transistor pair 464, 467 shown in the is arranged manner shown. The amplifier 74 receives be an input signal from envelope detector 44 at transistor 461 and a further input signal from inverter 68 via terminal 4 at the base input of transistor 464. Output signals generated at the collector of transistor 464 are, get through a buffer transistor 471 and a Terminal 5 to the switching device 82. A suitable circuit arrangement for the switching device 82 is shown in FIG shown.

According to Figure 5, the control signal at the output of the amplifier 74 via the terminal 5 and an emitter follower 586 to a Switching diode 588 coupled together with differential amplifier transistors 592, 593 and associated, in common base arranged transistors 594, 595 »which are arranged in the collector output circuits of transistors 592 and 595, forms part of the switching device 82. The base input of transistor 593 receives video signals from source 10, which are then transmitted via the collector-emitter path of transistor 595 to the collector output of this transistor. A color type for equenzfaU% §7, », äiP ^ aiis two equal parts

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87a VJdA 8? B, each with inductive and capacitive components, is coupled to the diode 588 and to the transistors 592-595 in the illustrated version. Output signals of the switching device 82 pass from the collector of the transistor 595 via an amplifier / buffer stage 590 and the chrominance blocking filter 95 to the luminance processing unit 100.

The mode of operation of the arrangement described is explained below with reference to the block diagram of FIG Of course, this explanation applies equally to the corresponding circuit arrangement shown in greater detail in FIGS fits.

The predetermined signal delay brought about by the delay unit 32 is chosen so that an interval is defined within which a transition or change of the color phase can occur. The delay time of 14-0 nanoseconds selected in the example described here corresponds to half a period of the color subcarrier signal (i.e. half of the eeziprok value of the color subcarrier frequency of 3.58 MHz) and represents against the approximately 63 microsecond long horizontal scanning interval represents a very small interval. It has been found that this delay time is for the purpose of determining the presence of an uncorrelatedness in the chrominance signal is appropriate, but other delay times can be used depending on the requirements of the particular system being used (e.g. odd or even multiples of half the period of the color subcarrier signal).

When dimensioning that to be effected by the delay unit 32 Delay should take into account how quickly phase transitions are expected to occur. The delay should be short enough to define an interval within which a rapid phase transition is complete or to can take place to a significant extent, since rapid phase transitions are the cause of the disruptive subcarrier sidebands are as mentioned above. In a system for processing color television signals, the speed becomes a

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Color phase transition that occurs within an interval of 500 Hanosecond is going on, near an upper limit for that too expected transition speeds. A delay time of 14-0 manoseconds is therefore suitable for determining the presence of rapid phase transitions Bauer is of this order of magnitude or less. It should be mentioned that with such a dimensioning of the delay the output side The control signal of the multiplier 25 turns out to be significantly lower if there is a very long phase transition (i.e. long compared with 14-0 Hano seconds) is. However, the effectiveness of the system will in this case not impaired, since very long phase transitions have few unwanted sideband components of the color carrier (if at all) and are therefore of little importance.

On the other hand, the one caused by the delay unit 32 should be Delay should not be excessively long compared to the duration of expected phase transitions. An inordinate delay is unsuitable for determining the presence of one or more rapid phase transitions, since then one or more such transitions can take place entirely within the delay interval. In such a case, the delayed and instantaneous chrominance signals to the inputs of the multiplier 25 are supplied, not the existence of a rapid phase transition accurately at the given point in time. Also, such a delay could lead to this lead that the multiplier 25 also lasts for a long time Responds to phase transitions of the type in which no significant unwanted sideband components of the color subcarrier be generated. The multiplier 25 would then have an unnecessary and undesirable control signal at its output deliver.

The signal multiplier 25 generates a negative control signal if the phases of the delayed and undelayed input signals are incorrect during any line scan interval. The amount of the initial

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signals is proportional to the degree of the difference in color phase, so that a maximum positive output signal a correlated state and a less positive (i.e. going in the negative direction) output signal of an uncorrelatedness is equivalent to.

The dependence of the amplitude of the output from the multiplier 25 Output signal on the frequency is with the curve A shown in Figure 6. According to this curve, the amplitude has a peak value at the subcarrier frequency of 3.58 MHz for one state of signal correlation and one Zero at half the subcarrier frequency for a state of maximum incorrectness of the signals. The peak value at and in the range of 0 Hz (direct current) comes into effect not before, since signal frequencies in this range differ from the frequency-selective frequency that passes through the band of chrominance signals Circuit 12 can be attenuated. A sharper response range in the vicinity of the subcarrier frequency can be achieved, if the delay unit 32 has a delay of Brings 440 nanoseconds, i.e. 3/2 times the color subcarrier period. The response behavior for this case is shown with curve B in FIG.

The control signal from the output of the multiplier 25 as Response to an incorrelated nature of the signals is generated contains high-frequency harmonics of the 3 »58 MHz auxiliary carrier next to the lower frequency component used for control purposes. The high frequency harmonics distort the Control component and are therefore attenuated with the low-pass filter 60, which in the example described here has a -3db bandwidth from 0 Hz (direct current) to 1.2 MHz. That from the filter 60 supplied filtered control signal is inverted by the inverter 68, so that a corresponding positively directed Control signal generated and given to one input of the amplifier 74.

The control signal from the multiplier 25 can be generated based on an un-

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correlatedness as well as due to (uncorrelated) high frequencies Luminance signals within the chrominance frequency band. It is therefore advantageous to provide an advertisement for which of these two signal conditions exists and is responsible for the signal generated by the multiplier 25. These Function is made common in the manner described below by the combination of envelope detector 44 and amplifier 74 met with the multiplier 25.

If at a control input of the amplifier 74 due to the Output of the multiplier 25 is a positive signal above a given threshold appears and at the same time the other control input of the amplifier 7 ^ - from the detector 44 receives a positive signal, which is also above the threshold value, then a means from Amplifier 74 emitted positively directed output signal, that there is an inaccuracy based on the chrominance information is due. This is because high-frequency luminance signals within the chrominance frequency band have a comparison to chrominance signals typically have a relatively short duration and are repeated non-periodically or sporadically. The diode 435 remains in the envelope curve detector 44 (cf. the embodiment according to FIG. 4) non-conductive and the detector 44 does not provide any demodulated which exceeds the threshold value Output signal when the duration of the high-frequency luminance signals does not exceed the switch-on time of the detector diode 435. Long-lasting, non-periodic luminance signals, which were sufficient to make the diode 435 conductive, could still not be sufficient to cause the detector 44 to generate an output signal of sufficient magnitude. this is because the time constant associated with filter elements 442, 444 and 445 of detector 44 is not a fast one Response to the peak amplitude of the (luminance) signals processed by detector 44 is allowed. This time constant is not critical, but it should be sufficiently larger than the period of the color subcarrier signal to allow envelope demodulation of the chrominance signals.

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In the presence of brief, non-periodic luminance signals In the band of chrominance frequencies, amplifier 74 does not receive a sufficient signal from the output of the detector 44. However, chrominance signals are essentially periodic in nature and have a longer duration than high-frequency luminance signals. The envelope detector 44- therefore responds to chrominance signals by emitting one which exceeds the threshold value Output signal when the chrominance signals are sufficiently strong. The amount of output from amplifier 74 The control signal is proportional to the magnitude of the signal that the multiplier 25 receives due to an incorrectness the color phase generated. This control signal is used to control the operation of the switching device 82 so that that the "color trap" 87 is coupled to the signals to be processed in the luminance channel, as shown below in FIG Connection with Figure 5 is explained.

In the absence of a positive control signal from amplifier 74 at terminal 5 (FIG. 5), if the condition is incorrect Chrominance signals is not met, the diode 588 is the in Figure 5 shown circuit non-conductive. Becomes a positive control signal from the amplifier due to an uncorrelation 74 is generated, then the diode 588 is thereby made conductive and thus for the sections 87a and 87b of the chrominance frequency trap a guiding path to earth created. Disturbing chrominance sideband frequencies in the signal at the collector of the transistor 593 appear and which are within the swallowing range of the color cases are therefore over the filter section 87a and conductive diode 588 are diverted to ground (i.e., they "trap") so that no contaminating chrominance signals appear at the collector output of transistor 595. This action is used in the Vesen to modify the frequency response of the amplitude for the luminance channel by adding the band stop range is expanded, which is otherwise in the luminance channel is defined by the notch filter 95. This effect is illustrated with the frequency response curves in FIG (drawn approximately to scale).

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Curve C in Figure 7 shows a frequency response characteristic for the suppression of the chrominance signal, as it is typically through a filter 95 arranged as a color carrier trap in the luminance channel a color television receiver is achieved. In the case shown, the trap has a -3db bandwidth of 0.62 MHz, which is roughly centered on the color subcarrier frequency of 3.58 MHz is so that signals within the frequency range 3.58 _ + 0.31 MHz are attenuated by 3 dB or more. If now that filter 87 arranged as a trap by the action of the amplifier 74- incoming control signal coupled to the luminance channel The filter characteristic of this trap (curve D) together with the filter characteristic of trap 95 (curve C) a combined effect in the suppression of the chrominance signals, as shown by curve E. In this case, signal frequencies are within a larger Bandwidth of 2.2 MHz, centered on the frequency 3 * 58 MHz, attenuated by 3db or more.

It should be mentioned that the bandwidth of the chrominance signals targeting blocking effect of the filter 87 as a function of the magnitude of the output signal from the multiplier 25 and the related output signal from the amplifier 7 ^ changes, these ^ signals in turn being proportional to the amount of uncorrelated color phase information. This effect results from the interaction of the reactive elements of the filter 87 with the forward impedance of the switching diode 588, when this on the control signal coming from the amplifier 74- leads there.

Diode 588 forms a minimum impedance to ground when they due to the maximum positive value of that coming from amplifier 74 Control signal conducts maximally in the forward direction. The filter 87 (e.g. section 87a of the trap) then has. a blocking effect of maximum bandwidth on chrominance signal frequencies, as shown by curve D in FIG. Thus, for the chrominance signal suppression obtained the combined bandwidth of 2.2 MHz (curve E in Figure 7). If the amount

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of the control signal becomes less positive, then this becomes maximum Blocking bandwidth is narrower in proportion to this.

A less positive control signal causes diode 588 to conduct less, so it has a higher forward impedance represents. This increased impedance of diode 588 in turn causes that the filter 87 brings a narrower stopband bandwidth, which in the same way reduces the combined stopband bandwidth created by the combination of the filter 95 and the controlled filter 87 is effected. In this sense, the diode 588 also serves as an active impedance element for the filter 87 to control the bandwidth.

The change in the conductivity of the diode 588 is therefore a means of achieving the maximum stopband bandwidth (curve E) of 2.2 HHz to a lesser degree between 2.2 and 0.62 MHz (each centered around the subcarrier frequency) when a less positive control signal indicates that less uncorrelated color phase information and thus fewer sideband components the chrominance signals are present. The narrower stopband bandwidth is sufficient, the sideband components generated in this case to suppress.

In summary, it can be said that the arrangement described modifies the frequency response of the luminance channel so that the sideband components expand into a wide band of the color subcarrier associated with states of uncorrelated Color phase go hand in hand, are attenuated in the luminance channel. Thus, disturbing edge spots, which in the case of uncorrelated occur and otherwise become visible in a reproduced image, suppressed or eliminated, so that the Quality of a reproduced image is improved.

The arrangement described above can be used alone or in conjunction can also be used with an arrangement which also improves the image quality, as described in a patent application of the same rank by the applicant (Representative File: RCA 72,017) which is based on U.S. Patent Application No. 859,863 decreases. The arrangement described there is reduced

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or eliminates annoying "crosstalk" into the color, which in a reproduced image could become visible if high frequency Luminance components appear within the band of chrominance components.

The arrangement described above is merely considered advantageous Embodiments of the invention to be considered, i.e., various modifications are possible without losing the range to leave the invention. If characteristic values for components and other examples of operating parameters are given these are only as an aid to understanding the invention and in no way to be regarded as a restriction.

It should also be mentioned that the in Figures 1 and 2 to 5 The embodiment shown feels and compensates for incorrect phase information that is more visible as the main cause Edge stains is to be seen. The illustrated embodiment however, it can also be designed to sense incorrect amplitude information. This can be done through this achieve that the amplitude limiters 15 and 40 takes away and the instantaneous signal from the frequency selective Circuit 12 and the delayed signal from delay unit 32 directly to the respective inputs of the multiplier 25 there. In this case it shows the output side Control signal of the multiplier 25 both incorrect amplitude information as well as incorrect phase information.

The control signal from the output of the multiplier 25 can the The operation of the switching device 82 can also be controlled directly without the need for an envelope detector such as 44 and an amplifier such as 74 is used. Other means can also be used, which acts on the output signal of the multiplier in addition to or in conjunction with the output signal of the amplifier 74 respond to suppress annoying edge stains. For example, the luminance channel could be amplified be controlled or blocked to prevent incorrect entry Chromaticity components in a rendered image

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or it could reduce the bandwidth selectivity that is often present in the luminance channel of a color television receiver Ink carrier trap (e.g. of the filter 95) in electronic Way to be controlled to achieve the same purpose. An arrangement for changing the bandwidth electronically of the luminance channel can be constructed, for example, similar to that described in U.S. Patent 3,924-266.

Finally, it should be noted that the delay unit 32 can be any suitable means for introducing a suitable Signal delay, e.g. one from charge transfer elements educated institution.

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Claims (12)

RCA Corporation, New York, fi.Y., V.St.ν.Α. An arrangement for suppressing impurities in the luminance signal caused by chrominance components in a television signal processing device; Patent claims: .; Arrangement for processing a color television signal for the Control of the luminance and the type of color of a reproduced color image depending on the image characteristics Luminance and chrominance components of the color television signal, wherein the chrominance component consists of modulated color subcarrier vibrations with a parameter tending to transitions and where special of these transitions with the appearance of sideband components of the secondary carrier are connected, which would bring an undesirable disturbance of the reproduced image, if they were essential Influence on the luminance of the image could be exerted with a luminance channel for processing the luminance component and having frequency selective means responsive to the color television signal for passing of signals that are limited to the frequency band occupied by the chrominance component, characterized by: 909824/0113 - 2 - ORIGINAL INSPECTED a delay device (32) for delaying the transmitted by the frequency-selective device (12) Signals by a time corresponding to an interval during which one of said special Transitions can occur; a detector (25) responsive to the input signal and on the output signal of the delay device responds and derives an output signal therefrom, which indicates the presence of one of the special transitions indicates; a control device responsive to this output signal (60,68, 74- with 4-4, 82, 87) to such Influence of the signals processed in the luminance channel (80) that the mentioned sideband components the wearer are prevented from to have a significant effect on the luminance of the reproduced color image. 2. Arrangement according to claim 1, characterized in that the parameter tending towards said transitions is the phase is the chrominance component. 3. Arrangement according to claim 2, characterized in that the delay device (32) brings a signal delay, which is equal to an odd multiple of half the period of the chrominance component. 4. Arrangement according to claim 2 or 3, characterized in that that the detector (25) has a signal multiplier, to feel the relative phases of the chrominance component and the delayed chrominance component. 5. Arrangement according to claim 4, characterized by a device (15 and 40) to limit the amplitude of the chrominance component and the delayed chrominance component supplied to the signal multiplier (25). 6. Arrangement according to one of claims 2 to 5? characterized by »09824/0913 -V- indicates that the control means includes sensing means (44) which, upon sensing the amplitude of the video signals one indicating the presence of the chrominance component Output signal provides, and that the control device a Contains control signal transmitter (74), which acts on the output signal the sensing device and the output signal of the detector (25) responds in order to deliver a control signal in the event of temporal coincidence of these output signals, which the Presence of one of the named special phase transitions indicates, and that this control signal is coupled to the luminance channel (80) to control the luminance signal im Meaning of a suppression of the mentioned sideband components to influence. 7. Arrangement according to claim 6, characterized in that the sensing device (44) the amplitude envelope of the delayed Chrominance component feels. 8. Arrangement according to claim 6, characterized in that the The amount of the control signal is proportional to the amount of the output signal of the detector (25). 9. Arrangement according to one of the preceding claims, characterized characterized in that the control circuit includes a second frequency selective device (87) and one with this second frequency-selective device having coupled switching device, which is based on the output signal of the detector (25) responds in order to couple the second frequency-selective device to the luminance channel (80) in such a way that that the mentioned sideband components in the luminance channel be suppressed. 10. The arrangement according to claim 9 »characterized in that the switching device (82) contains an active element of controllable conductivity in order to control the operation of the second frequency-selective device (87) such that the sideband components mentioned within one of the magnitude of the output signal of the detector ( 25) specific frequency range can be suppressed. _Ä _ " 009824/0911 11. The arrangement according to claim 10, characterized in that the active element of controllable conductivity is a semiconductor element (588 in Figure 5), which is a dynamic Passage impedance when conducting depends on the output signal of the detector (25). 12. The arrangement according to claim 9 »characterized in that the second frequency-selective device (95) in the luminance channel (80) is to attenuate a first range of chrominance signal frequencies and that the control means further includes a third frequency selective means (87) for chrominance signal frequencies within to attenuate a frequency range which is greater than the first frequency range ', and that the switching device (82) -dependent on the third frequency selective device from the output signal of the detector (25) with the luminance channel couples.